kenzier093 -- maybe try applying the Poultry Dust more often (like once every week) so that you can get it under control. Probably what is happening is that the eggs are hatching between your application times. I've used the Poultry Dust and it cleared up my mite problem. But I clean out the coop bedding (pine shavings) every week and dust inside of the coop and nesting boxes each time to help keep it under control. But if you are having an infestation problem, I would recommend that you dust your birds and coop weekly until you get it under control.
LittleRedCoop53 -- I think the DE is fine if your birds or coop isn't already infested with bugs, so I'd continue using it. Just be sure that you check your birds periodically (especially if you see them shake their heads) for bugs.